This invention relates generally to three dimensional coordinate measuring machines (or CMM's). More particularly, this invention relates to a new and improved three dimensional CMM which is portable and provides improved accuracy and ease of use; and the application of this CMM to a novel method for constructing 3-dimensional maps of a measurable quantity such as temperature, coating thickness, density or the like.
It will be appreciated that everything in the physical world occupies volume or space. Position in a space may be defined by length, width and height which, in engineering terms, is often called an X, Y, Z coordinate. The X, Y, Z numbers represent the dimensions of length, width and height or three dimensions. Three-dimensional objects are described in terms of position and orientation; that is, not just where an object is but in what direction it points. The orientation of an object in space can be defined by the position of three points on the object. Orientation can also be described by the angles of alignment of the object in space. The X, Y, and Z coordinates can be most simply measured by three linear scales. In other words, if you lay a scale along the length, width and height of a space, you can measure the position of a point in the space.
Presently, coordinate measurement machines or CMM's measure objects in a space using three linear scales. These devices are typically non-portable, expensive and limited in the size or volume that can be easily measured.
FARO Technologies, Inc. of Lake Mary, Fla. (the assignee of the present invention) has successfully produced a series of electrogoniometer-type digitizing devices for the medical field. In particular, FARO Technologies, Inc. has produced systems for skeletal analysis known as METRECOM.RTM. and systems for use in surgical applications known as SURGICOM.TM.. Electrogoniometer-type devices of the type embodied in the METRECOM and SURGICOM systems are disclosed in U.S. Pat. Nos. 4,670,851 and 5,251,127 and 5,305,203 all of which are assigned to the assignee hereof and incorporated herein by reference.
While well suited for their intended purposes, the METRECOM and SURGICOM electrogoniometer-type digitizing systems are not well suited for general industrial applications where three dimensional measurements of parts and assemblies are often required. Therefore, there is a continuing need for improved, accurate and low cost CMM's for industrial and related applications.